Facts About Norwalk-like Viruses: CDC-OC
Article title: Facts About Norwalk-like Viruses: CDC-OC
Conditions: Norwalk-like Viruses
Source: CDC-OC
Norwalk-like
Viruses
November 28, 1997
Contact: Media Relations Division
(404) 6393286
- Norwalk viruses (and related caliciviruses) are important causes of
sporadic and epidemic gastrointestinal disease in the United States. An
estimated 181,000 cases occur annually.
- Viral gastroenteritis due to caliciviruses has been associated with
eating contaminated oysters. Oysters can become contaminated
before harvest or during preparation. Water and ice are other
sources of infection.
- Symptoms of Norwalk virus infection include nausea, vomiting,
diarrhea, and abdominal cramps. Headache and low-grade fever may also
occur. Persons with this infection usually recover within 2-3 days
without serious or long-term health effects.
- Shellfish become contaminated via infected fecal matter from sick
food handlers, or by the practice of some harvesters and/or recreational
boaters of dumping raw sewage overboard. (Note: the only source of
calicivirus is feces from sick persons.)
- Since 1993, three oyster-related gastroenteritis outbreaks,
attributed to calicivirus, have been documented in Louisiana. In 1993,
73 persons in Louisiana and about 130 others in the United States who
ate oysters from Louisiana became ill. A malfunctioning sewage system
was the cause of an outbreak in 1996. The current outbreak implicates
sewage from oyster harvesting vessels as the probable source.
- Oyster-related outbreaks probably will continue to occur until
seafood regulators and the oyster industry develop and enforce standards
for proper disposal of human sewage. Food handlers with symptoms of
Norwalk-like illness should limit contact with other persons and be
excluded from food handling and preparation.
This page last reviewed
URL:
Centers for
Disease Control and Prevention
Office of
Communication
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